Piston



Filed Apr il 6, 1934 2 Sheets-Sheet 1 A Vol' -K 4/ Emanuel VQlen'h a INVENTOR BY k ATTORNEY April 7, 1936.

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A. vALAEK -E.T AL

PISTON Filed April 6, 1934 2 Sheets-Sheet 2 @IJZZIi/Iflllllilll V lnueniom Ado lfiValq's k P Emanuel Valenila ATTORNEY lid , by the stidening means in a manner which, in

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*tehied Apn. 7, 1936 hdddglid FMSTUN vairia Application April #8, 1934i, Serial No. "$19,237 in waechoalovakia dpril i9, 193% ML-1 invention relates to a piston, the head and skirt oi which are connected together by coecting elements carrying the gudgeon pin hearings. in the pistons of this type which are already known, stiiiening means are provided in addition to the connecting elements, the said stidening means being made of a material oi smaller coemcient of V expansion than that of the connecting elements or piston. Such pistons suder from various disadvantages. They constitute a rigid system, in which the unusually large expansion of certain parts oi the piston, particularly the skirt, the said large expansion being due to the high coeificient oi expansion oi the material of which the piston is de (light metal alloys), is compensated addition to being complicated, is also insuiiicient. A further disadvantage of the known pistons oi this kind is their complicated construction.

The object of this invention is to provide a piston oi the kind referred to hereinbeiore, which piston possesses great strength, is of simple construction, being capable of manufactures by casting, and whose skirt in addition has a resilient efiect to such a considerable extent that the skirt can follow every expansion due to the material of which the piston is made. Accor to the invention, this is accomplished by the iact that the piston skirt is composed oi two parts, which are disposed in overhung manner *on the connecting elements carrying the gudgeon pin bearings such that each connecting element is connected with one of the parts oi the piston skirt.

it constructional example oi the piston according to the invention is shown in the accompanying drawings, in which:

Figure 1 shows diagrammatically in perspective the principle on which the piston is based.

Figure 1a shows one embodiment in side elevation.

Figure 2 shows another embodiment oi the piston in side elevation.

Figure 3 shows a section along the line mm in Fl E.

Fie i is a section along the line Iii-TV in Figure 2i.

Figures 5 and 6 are cross-sections along the lines tT-V and VT- V1, respectively, in Figure 2.

I! is the piston head which is provided in its cylindrical part i with grooves d for the piston a, e piston head i is connected to the skirt of the piston by elements t carrying the bearings t tor the gudgeonpin.

The piston skirt is composed of two parts M, it, which are disposed in overhung manner on the connecting elements i carrying the gudgeon pin bearings t, such that each connecting element is connected to one oi the skirt parts M, or ii, respectively. The gaps extending between the piston head i and the skirt parts it, it are shown at d, and the separating slits extending between the skirt parts M, ii are shown at it.

In the constructional example shown in the drawings, the connecting elements i consists oi two stays disposed'cross-wise with respect to each other, and so arranged with respect to the piston axial plane EE passing through the gudgeon pin bearings t that the points oi attachment til, it oi the stays i on the piston head i, and the points of attachment ii, ii of the stays i on the skirt parts ill, it lie on diiierent sides oi the piston axial plane E-E. in addition, the points oi attachment it to it are disposed in alternate arrangement, that is to say, the points it, it oi the stay i corresponding to one skirt part ii, and the points of attachment ii, it of the stay i corresponding to the other skirt part it are on difierent sides of the piston axial plane E-E. The axes A-A and B-B oi the stays i seen in the axial direction of the gudgeon pin cross each other in the axis of the gudgeon pin and each make an angle a. with the piston axial plane lE-E. The angle at which the two axes A--A. and B--B oi the stays cross each other is thereiore fiat.

Those parts oi the stays which are situated between the gudgeon pin bearings h and the piston head i may be constructed in a manner diiierent from that described in the foregoing. For example, the said stay parts may lie in the piston axial plane E--E. Those parts oi the stays it which are situated below the gudgeon pin bearings t are in this case divergent with respect to each other, such that the points of attachment it, it oi the stays d on the skirt parts Ill, ii lie on diflerent sides oi the piston axial plane E-E passing through the gudgeon pin bearings b. This is shown in Fig. la.

The separating slits it which subdivide the piston skirt into its parts are disposed. below the gudgeon pin bearings t. The separating slits it may be either parallel to the piston axial plane E-E or inclined at an angle there to. In the constructional example shown in the wings, the separating slits are inclined at an angle a to the piston axial plane E--E, and in different directions with respect to the plane 11-13, as are also the stays 4 situated near the separating slits.

In order to provide connecting stays 4 of rigid construction and yet of light weight, the said connecting stays are stiffened by stiffening means, in the present constructional example, by stiffening ribs 1, 8. The stifiening ribs 1 for that part of the stays 4 which is situated above the gudgeon pin bearings 5 engage the piston head I deeply andarearrangedinpairsinorder to provide a particularly robust connection of the gudgeon pin bearings 5 with the piston head. The stiffening ribs 8 extend in the middle of the lower part of the stay 4;

In order to influence the degree of resiliency of the skirt parts H, I2 in accordance with the requirements which the piston has to satisfy, suitable means may be provided for stifiening the skirt parts. A possible means for such stiifening of the skirt parts ll, 12 is to provide ribs l3 starting from the lower ends of the stays 4 and extending over the periphery of the piston skirt or parts thereof. The ribs I3 may be either horizontal or in spiral form starting from the stays 4 and extending towards the lower edge of the piston skirt. Tests have shown that more particularly the stiilening of the skirt parts by the spiral ribs affords special advantages in regard to the resiliency of the piston skirt, and in addition reliably eliminates the danger of fatigue of the material.

The piston described in the foregoing satisfies all requirements which the operation of internal combustion engines demands of a satisfactory piston construction. The heat of the piston head is conducted by a suiliciently large crossscction of the stays 4 through the gudgeon pin bearings 5 to the lower portions of the skirt halves, and only from thence does the heat reach the upper portions of the skirt halves. On this long path, the flow of heat is diminished by the cooling effect of the oil flowing round the stays and gudgeon pin bearings and a good escape of heat through the cylinder walls is also ensured. An approximately uniform and low heating of the piston skirt, and consequently a comparatively small expansion over the entire height of the piston is also secured thereby. Due to the overhung attachment of the skirt parts II, l2 to the connecting elements 4, in combination with the cross-wise arrangement of the connecting elements, the rigid parts of the piston skirt are located in the vicinity of the piston axial plane E-E, that is to say, they are removed as far as possible from the place where there is the greatest danger of seizing. In this way, the

danger of seizing and the danger of material fractures are eliminated, since the piston is not stressed mechanically at all at the places where there is a tendency to seize. Due to the fact that the most resilient places of the skirt are diametrically opposite the still places, there results, apart from good resiliency, also a rational distribution of the degree of resiliency over the entire periphery of the skirt, and displacement or twisting of the gudgeon pin out of its central position is most effectively prevented.

A further advantage of the present piston is that it only possesses a few parts, and consequently only a few transition places, which may easily be so constructed as to eliminate the dango:- of fatigue or fracture at such places, particularly at the points of attachment of the connecting stays 4 on the skirt parts.

We claim:

1. A piston comprising a head portion, two skirt portions, connecting elements between the head portion and each skirt portion, gudgeon pin bearings in said connecting elements, and ribs extending spirally round the inner surface of the skirt portions from the junctions of the connecting elements with said portions.

2. A piston comprising a head portion, two skirt portions separated from each other by slits, a single connecting strut between the head portion and each skirt portion, gudgeon pin bosses in said connecting struts located above the slits and intermediate the ends of said struts, the junction between said struts and their respective skirt portions being located only on one side of the slits between the skirt portions, and the junction of one strut lying on one side of a plane containing the piston axis and the pin boss axis, and the junction between the other strut and its skirt portion lying on the other side of said plane, so that the strut parts situated between the gudgeon pin bosses and the skirt portions cross one another when viewed in the direction of the gudgeon p n axis.

3. A piston according to claim 2, and in which the junction between the connecting struts and their associated head and skirt portion! are on alternate sides of the plane containing the piston and gudgeon pin boss axes, so that the struts in their whole length cross one another when viewed in the direction of the gudgeon pin axis.

4. A piston according to claim 2, and in which the slits between the skirt portions and the struts are inclined in opposite directions with respect to the axial plane of the piston containing the gudgeon pin bosses.

- ADOLF VALASEK.

EMANUEL VALENTA. 

